The present invention relates to a motion detector for monitoring the movement of a body, and more particularly relates to an alarm device for monitoring the activity of a person to provide an alarm signal if the person becomes immobile as a result of an injury.
There are many situations in which an alarm device is useful. For example, a person working in a dangerous environment, such as a fireman or miner, may attach such a device to his clothing to monitor his movements. If the worker is injured and thereby immobilized, the device provides an alarm signal to summon aid for the injured worker. Also, an elderly person may desire to wear such a device to summon aid if he is immobilized due to an injury. Furthermore, an alarm device may be adapted for use in a variety of other situations. For example, the device may be adapted for use as a security device for an inanimate body, such as a motor vehicle, to detect unauthorized movement of the inanimate body.
Many different types of motion detectors are known which may be used as an alarm device. However, in large part, these detectors do not have a motion sensor having a three axis motion sensing capability and the sensitivity of their motion sensors is not easily adjustable. Also, these detectors may be complex and bulky in structure, expensive to manufacture, and are not light weight. Additionally, these detectors usually are not watertight and shock resistant and, in general, are not suited for use in unfavorable environments. Furthermore, these detectors may require frequent maintenance and/or replacement and are not capable of testing themselves to ensure that they are operating properly. Still further, these detectors may generate false alarm signals due to momentary inactivity by a person wearing the detector. Still further, these detectors, usually do not have alarms which generate a warning signal, before a high level alarm signal is generated, so that a person wearing the detector can act to prevent activation of the high level alarm signal when the person desires to remain motionless for a long time period. Also, these detectors usually do not have an alarm which may be manually operated. These disadvantages limit the situations in which these motion detectors may be used.